A test-pit is a small exploratory hole, usually square and 1 x 1 or 2 x 2 metres. A number of test-pits are sometimes dug on a site to get a snapshot of the archaeology below as part of the evaluation process. The advantages of this method are that it is quick and, if the test-pits are regularly spaced, the archaeologist can get what is hopefully a representative sample of the types of archaeological remains in that area.
The difficulty with this method is that the very small areas do not allow an appreciation of the extent or complexity of archaeological features. Also, because the test-pits are so small and so far apart, large areas of archaeology can be missed. Archaeological remains are not scattered at a constant rate across the landscape but are often concentrated at certain locations.
Test-pits are not routinely used as a method of site detecting in commercial archaeology. If they are dug they are used to understand and date the soil-build up since the occupation of the site. It may also be an alternative to field-walking where remains are deeply buried or on land that is not ploughed.